In the operation of wheeled vehicles, such as off-highway trucks, it is desirable to utilize a relatively low spring rate, soft suspension system. However, such soft suspension systems raise a serious problem in connection with the tendency of the vehicle to roll in a turn or on a slope.
Further, it is desirable to provide in such off-highway vehicles a relatively wide tire. On the rear axle, it is conventional to use a pair of tires on each side of the vehicle. Where such wide tires are utilized, the availability of space for mounting the suspension system struts therebetween is substantially reduced, requiring that the struts be disposed relatively closely together. Reduction in the spring rate of such a suspension system, as well as such juxtaposition of the struts, causes a substantial reduction in the roll resistance.
Conventionally, off-highway vehicles have relatively high centers of gravity. As a result of such reduction in the spring rate of the front struts, such vehicles tend to roll in a turn or on a side slope. As a result, they transfer greater loads to the outboard strut, causing the strut to contract and thus further aggravate the problem.
In U.S. Pat. No. 3,871,635 of Dale H. Unruh et al., which patent is owned by the assignee hereof, a suspension hydraulic roll stabilizer with leveling is disclosed. In that patent, the hydraulic struts are cross-connected across the vehicle, with each of the cross connections being provided with a gas-charged accumulator for providing a spring rate for each hydraulic system. Leveling is effected by selective transfer of hydraulic fluid between the otherwise cross-connected strut systems. The strut construction required a relativley large size to provide suitable strength for the load.
The present problem is directed to overcoming one or more of the problems set forth.